1. Field of the Invention
This invention relates to the epoxidation of olefins and more particularly, to the use of inorganic phosphates as catalyst enhancers.
2. Description of the Prior Art
Epoxidation of ethylene can be rather simply and easily done on a commercial scale. However, epoxidation of higher olefins beginning with propylene is much more difficult to accomplish on a commercial scale. Previously, this had been done by a complicated chlorohydrin process and more recently, through the use of a soluble metal catalyst such as disclosed in U.S. Pat. Nos. 3,351,635 and 3,350,422. After the discovery of the catalytic effect of the soluble metal catalyst, a search was begun for methods of improving the catalytic activity of such metals. This search has concentrated on both soluble and insoluble forms of the metal catalyst.
German Pat. No. 2,231,374 sets forth an insoluble catalyst for the reaction of olefins with hydroperoxides to yield epoxides. The catalyst consist either of compounds of the elements of Groups IV to VI of the secondary system of the periodic system with tin, phosphorous, arsenic, antimony, bismuth, selenium and/or tellurium or of mixtures of these compounds, or of mixtures of compounds of the elements of the secondary Groups IV to VI and the elements of the main groups IV to VI.
U.S. Pat. No. 3,526,645 sets forth the epoxidation of olefins using a compound of a metal selected from Groups IV, V and VI of the periodic table of elements mixed with a compound of a metal selected from Groups VII and VIII of the periodic table of elements.
U.S. Pat. No. 3,843,694 sets forth the use of boron phosphate to catalyze the oxidation of ethylenically unsaturated organic compounds to oxiranes with the use of an organic hydroperoxide.
U.S. Pat. No. 3,870,729 sets forth a process for the epoxidation of an olefinic compound by contacting the compound with an organic hydroperoxide in the presence of a soluble titanium compound and a phosphoric acid ester.
German Pat. No. 2,446,830 dated Apr. 3, 1975 (Chemical Abstracts 83, 58637t) sets forth a process for the epoxidation of olefins using hydrogen peroxide and a catalyst, one of the catalyst includes a lead phosphate.
Japanese Pat. No. 74 45,843 dated Dec. 6, 1974 (Chemical Abstracts 82, 171686a) sets forth the epoxidation of propylene to propylene oxide using an alkali metal phosphate and oxygen under high pressure and temperature.